1 ;;;; This file implements type check generation. This is a phase that
2 ;;;; runs at the very end of IR1. If a type check is too complex for
3 ;;;; the back end to directly emit in-line, then we transform the check
4 ;;;; into an explicit conditional using TYPEP.
6 ;;;; This software is part of the SBCL system. See the README file for
9 ;;;; This software is derived from the CMU CL system, which was
10 ;;;; written at Carnegie Mellon University and released into the
11 ;;;; public domain. The software is in the public domain and is
12 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
13 ;;;; files for more information.
19 ;;; Return some sort of guess about the cost of a call to a function.
20 ;;; If the function has some templates, we return the cost of the
21 ;;; cheapest one, otherwise we return the cost of CALL-NAMED. Calling
22 ;;; this with functions that have transforms can result in relatively
23 ;;; meaningless results (exaggerated costs.)
25 ;;; We special-case NULL, since it does have a source tranform and is
26 ;;; interesting to us.
27 (defun fun-guessed-cost (name)
28 (declare (symbol name
))
29 (let ((info (info :function
:info name
))
30 (call-cost (template-cost (template-or-lose 'call-named
))))
32 (let ((templates (fun-info-templates info
)))
34 (template-cost (first templates
))
36 (null (template-cost (template-or-lose 'if-eq
)))
40 ;;; Return some sort of guess for the cost of doing a test against
41 ;;; TYPE. The result need not be precise as long as it isn't way out
42 ;;; in space. The units are based on the costs specified for various
43 ;;; templates in the VM definition.
44 (defun type-test-cost (type)
45 (declare (type ctype type
))
46 (or (when (eq type
*universal-type
*)
48 (when (eq type
*empty-type
*)
50 (let ((check (type-check-template type
)))
53 (let ((found (cdr (assoc type
*backend-type-predicates
*
56 (+ (fun-guessed-cost found
) (fun-guessed-cost 'eq
))
60 (reduce #'+ (compound-type-types type
) :key
'type-test-cost
))
62 (* (length (member-type-members type
))
63 (fun-guessed-cost 'eq
)))
65 (* (if (numeric-type-complexp type
) 2 1)
67 (if (csubtypep type
(specifier-type 'fixnum
)) 'fixnump
'numberp
))
69 (if (numeric-type-low type
) 1 0)
70 (if (numeric-type-high type
) 1 0))))
72 (+ (type-test-cost (specifier-type 'cons
))
73 (fun-guessed-cost 'car
)
74 (type-test-cost (cons-type-car-type type
))
75 (fun-guessed-cost 'cdr
)
76 (type-test-cost (cons-type-cdr-type type
))))
78 (fun-guessed-cost 'typep
)))))
81 (weaken-type :hash-bits
8
82 :hash-function
(lambda (x)
83 (logand (type-hash-value x
) #xFF
)))
85 (declare (type ctype type
))
86 (let ((min-cost (type-test-cost type
))
89 (dolist (x *backend-type-predicates
*)
90 (let ((stype (car x
)))
91 (when (and (csubtypep type stype
)
92 (not (union-type-p stype
)))
93 (let ((stype-cost (type-test-cost stype
)))
94 (when (or (< stype-cost min-cost
)
96 ;; If the supertype is equal in cost to the type, we
97 ;; prefer the supertype. This produces a closer
98 ;; approximation of the right thing in the presence of
102 min-cost stype-cost
))))))
107 (defun weaken-values-type (type)
108 (declare (type ctype type
))
109 (cond ((eq type
*wild-type
*) type
)
110 ((not (values-type-p type
))
113 (make-values-type :required
(mapcar #'weaken-type
114 (values-type-required type
))
115 :optional
(mapcar #'weaken-type
116 (values-type-optional type
))
117 :rest
(acond ((values-type-rest type
)
118 (weaken-type it
)))))))
120 ;;;; checking strategy determination
122 ;;; Return the type we should test for when we really want to check
123 ;;; for TYPE. If type checking policy is "fast", then we return a
124 ;;; weaker type if it is easier to check. First we try the defined
125 ;;; type weakenings, then look for any predicate that is cheaper.
126 (defun maybe-weaken-check (type policy
)
127 (declare (type ctype type
))
128 (ecase (policy policy type-check
)
130 (2 (weaken-values-type type
))
133 ;;; This is like VALUES-TYPES, only we mash any complex function types
135 (defun no-fun-values-types (type)
136 (declare (type ctype type
))
137 (multiple-value-bind (res count
) (values-types type
)
138 (values (mapcar (lambda (type)
139 (if (fun-type-p type
)
140 (specifier-type 'function
)
145 ;;; Switch to disable check complementing, for evaluation.
146 (defvar *complement-type-checks
* t
)
148 ;;; LVAR is an lvar we are doing a type check on and TYPES is a list
149 ;;; of types that we are checking its values against. If we have
150 ;;; proven that LVAR generates a fixed number of values, then for each
151 ;;; value, we check whether it is cheaper to then difference between
152 ;;; the proven type and the corresponding type in TYPES. If so, we opt
153 ;;; for a :HAIRY check with that test negated. Otherwise, we try to do
154 ;;; a simple test, and if that is impossible, we do a hairy test with
155 ;;; non-negated types. If true, FORCE-HAIRY forces a hairy type check.
157 ;;; When doing a non-negated check, we call MAYBE-WEAKEN-CHECK to
158 ;;; weaken the test to a convenient supertype (conditional on policy.)
159 ;;; If SPEED is 3, or DEBUG-INFO is not particularly important (DEBUG
160 ;;; <= 1), then we allow weakened checks to be simple, resulting in
161 ;;; less informative error messages, but saving space and possibly
164 ;;; FIXME: I don't quite understand this, but it looks as though
165 ;;; that means type checks are weakened when SPEED=3 regardless of
166 ;;; the SAFETY level, which is not the right thing to do.
167 (defun maybe-negate-check (lvar types original-types force-hairy n-required
)
168 (declare (type lvar lvar
) (list types original-types
))
169 (let ((ptypes (values-type-out (lvar-derived-type lvar
) (length types
))))
170 (multiple-value-bind (hairy-res simple-res
)
171 (loop for p in ptypes
173 and a in original-types
175 for cc
= (if (>= i n-required
)
176 (type-union c
(specifier-type 'null
))
178 for diff
= (type-difference p cc
)
179 collect
(if (and diff
180 (< (type-test-cost diff
)
182 *complement-type-checks
*)
186 collect cc into simple-res
187 finally
(return (values hairy-res simple-res
)))
188 (cond ((or force-hairy
(find-if #'first hairy-res
))
189 (values :hairy hairy-res
))
190 ((every #'type-check-template simple-res
)
191 (values :simple simple-res
))
193 (values :hairy hairy-res
))))))
195 ;;; Determines whether CAST's assertion is:
196 ;;; -- checkable by the back end (:SIMPLE), or
197 ;;; -- not checkable by the back end, but checkable via an explicit
198 ;;; test in type check conversion (:HAIRY), or
199 ;;; -- not reasonably checkable at all (:TOO-HAIRY).
201 ;;; We may check only fixed number of values; in any case the number
202 ;;; of generated values is trusted. If we know the number of produced
203 ;;; values, all of them are checked; otherwise if we know the number
204 ;;; of consumed -- only they are checked; otherwise the check is not
207 ;;; A type is simply checkable if all the type assertions have a
208 ;;; TYPE-CHECK-TEMPLATE. In this :SIMPLE case, the second value is a
209 ;;; list of the type restrictions specified for the leading positional
214 ;;; We force a check to be hairy even when there are fixed values
215 ;;; if we are in a context where we may be forced to use the
216 ;;; unknown values convention anyway. This is because IR2tran can't
217 ;;; generate type checks for unknown values lvars but people could
218 ;;; still be depending on the check being done. We only care about
219 ;;; EXIT and RETURN (not MV-COMBINATION) since these are the only
220 ;;; contexts where the ultimate values receiver
222 ;;; In the :HAIRY case, the second value is a list of triples of
224 ;;; (NOT-P TYPE ORIGINAL-TYPE)
226 ;;; If true, the NOT-P flag indicates a test that the corresponding
227 ;;; value is *not* of the specified TYPE. ORIGINAL-TYPE is the type
228 ;;; asserted on this value in the lvar, for use in error
229 ;;; messages. When NOT-P is true, this will be different from TYPE.
231 ;;; This allows us to take what has been proven about CAST's argument
232 ;;; type into consideration. If it is cheaper to test for the
233 ;;; difference between the derived type and the asserted type, then we
234 ;;; check for the negation of this type instead.
235 (defun cast-check-types (cast force-hairy
)
236 (declare (type cast cast
))
237 (let* ((ctype (coerce-to-values (cast-type-to-check cast
)))
238 (atype (coerce-to-values (cast-asserted-type cast
)))
239 (dtype (node-derived-type cast
))
240 (value (cast-value cast
))
241 (lvar (node-lvar cast
))
242 (dest (and lvar
(lvar-dest lvar
)))
243 (n-consumed (cond ((not lvar
)
245 ((lvar-single-value-p lvar
)
247 ((and (mv-combination-p dest
)
248 (eq (mv-combination-kind dest
) :local
))
249 (let ((fun-ref (lvar-use (mv-combination-fun dest
))))
250 (length (lambda-vars (ref-leaf fun-ref
)))))))
251 (n-required (length (values-type-required dtype
))))
252 (aver (not (eq ctype
*wild-type
*)))
253 (cond ((and (null (values-type-optional dtype
))
254 (not (values-type-rest dtype
)))
255 ;; we [almost] know how many values are produced
256 (maybe-negate-check value
257 (values-type-out ctype n-required
)
258 (values-type-out atype n-required
)
259 ;; backend checks only consumed values
260 (not (eql n-required n-consumed
))
262 ((lvar-single-value-p lvar
)
263 ;; exactly one value is consumed
264 (principal-lvar-single-valuify lvar
)
265 (flet ((get-type (type)
266 (acond ((args-type-required type
)
268 ((args-type-optional type
)
270 (t (bug "type ~S is too hairy" type
)))))
271 (multiple-value-bind (ctype atype
)
272 (values (get-type ctype
) (get-type atype
))
273 (maybe-negate-check value
274 (list ctype
) (list atype
)
277 ((and (mv-combination-p dest
)
278 (eq (mv-combination-kind dest
) :local
))
279 ;; we know the number of consumed values
280 (maybe-negate-check value
281 (adjust-list (values-type-types ctype
)
284 (adjust-list (values-type-types atype
)
290 (values :too-hairy nil
)))))
292 ;;; Do we want to do a type check?
293 (defun cast-externally-checkable-p (cast)
294 (declare (type cast cast
))
295 (let* ((lvar (node-lvar cast
))
296 (dest (and lvar
(lvar-dest lvar
))))
297 (and (combination-p dest
)
298 ;; The theory is that the type assertion is from a
299 ;; declaration in (or on) the callee, so the callee should be
300 ;; able to do the check. We want to let the callee do the
301 ;; check, because it is possible that by the time of call
302 ;; that declaration will be changed and we do not want to
303 ;; make people recompile all calls to a function when they
304 ;; were originally compiled with a bad declaration. (See also
306 (or (immediately-used-p lvar cast
)
307 (binding* ((ctran (node-next cast
) :exit-if-null
)
308 (next (ctran-next ctran
)))
310 (eq (node-dest next
) dest
)
311 (eq (cast-type-check next
) :external
))))
312 (values-subtypep (lvar-externally-checkable-type lvar
)
313 (cast-type-to-check cast
)))))
315 ;;; Return true if CAST's value is an lvar whose type the back end is
316 ;;; likely to want to check. Since we don't know what template the
317 ;;; back end is going to choose to implement the continuation's DEST,
318 ;;; we use a heuristic. We always return T unless:
319 ;;; -- nobody uses the value, or
320 ;;; -- safety is totally unimportant, or
321 ;;; -- the lvar is an argument to an unknown function, or
322 ;;; -- the lvar is an argument to a known function that has
323 ;;; no IR2-CONVERT method or :FAST-SAFE templates that are
324 ;;; compatible with the call's type.
325 (defun probable-type-check-p (cast)
326 (declare (type cast cast
))
327 (let* ((lvar (node-lvar cast
))
328 (dest (and lvar
(lvar-dest lvar
))))
329 (cond ((not dest
) nil
)
332 (cond ((or (not dest
)
333 (policy dest
(zerop safety
)))
335 ((basic-combination-p dest
)
336 (let ((kind (basic-combination-kind dest
)))
338 ((eq cont
(basic-combination-fun dest
)) t
)
343 (and (combination-p dest
)
344 (not (values-subtypep ; explicit THE
345 (continuation-externally-checkable-type cont
)
346 (continuation-type-to-check cont
)))))
347 ;; :ERROR means that we have an invalid syntax of
348 ;; the call and the callee will detect it before
349 ;; thinking about types.
352 (let ((info (basic-combination-fun-info dest
)))
353 (if (fun-info-ir2-convert info
)
355 (dolist (template (fun-info-templates info
) nil
)
356 (when (eq (template-ltn-policy template
)
358 (multiple-value-bind (val win
)
359 (valid-fun-use dest
(template-type template
))
360 (when (or val
(not win
)) (return t
)))))))))))))
363 ;;; Return a lambda form that we can convert to do a hairy type check
364 ;;; of the specified TYPES. TYPES is a list of the format returned by
365 ;;; LVAR-CHECK-TYPES in the :HAIRY case.
367 ;;; Note that we don't attempt to check for required values being
368 ;;; unsupplied. Such checking is impossible to efficiently do at the
369 ;;; source level because our fixed-values conventions are optimized
370 ;;; for the common MV-BIND case.
371 (defun make-type-check-form (types)
372 (let ((temps (make-gensym-list (length types
))))
373 `(multiple-value-bind ,temps
375 ,@(mapcar (lambda (temp type
)
377 (let ((*unparse-fun-type-simplify
* t
))
378 (type-specifier (second type
))))
379 (test (if (first type
) `(not ,spec
) spec
)))
380 `(unless (typep ,temp
',test
)
383 ',(type-specifier (third type
))))))
388 ;;; Splice in explicit type check code immediately before CAST. This
389 ;;; code receives the value(s) that were being passed to CAST-VALUE,
390 ;;; checks the type(s) of the value(s), then passes them further.
391 (defun convert-type-check (cast types
)
392 (declare (type cast cast
) (type list types
))
393 (let ((value (cast-value cast
))
394 (length (length types
)))
395 (filter-lvar value
(make-type-check-form types
))
396 (reoptimize-lvar (cast-value cast
))
397 (setf (cast-type-to-check cast
) *wild-type
*)
398 (setf (cast-%type-check cast
) nil
)
399 (let* ((atype (cast-asserted-type cast
))
400 (atype (cond ((not (values-type-p atype
))
403 (single-value-type atype
))
406 :required
(values-type-out atype length
)))))
407 (dtype (node-derived-type cast
))
408 (dtype (make-values-type
409 :required
(values-type-out dtype length
))))
410 (setf (cast-asserted-type cast
) atype
)
411 (setf (node-derived-type cast
) dtype
)))
415 ;;; Check all possible arguments of CAST and emit type warnings for
416 ;;; those with type errors. If the value of USE is being used for a
417 ;;; variable binding, we figure out which one for source context. If
418 ;;; the value is a constant, we print it specially.
419 (defun cast-check-uses (cast)
420 (declare (type cast cast
))
421 (let* ((lvar (node-lvar cast
))
422 (dest (and lvar
(lvar-dest lvar
)))
423 (value (cast-value cast
))
424 (atype (cast-asserted-type cast
)))
426 (let ((dtype (node-derived-type use
)))
427 (unless (values-types-equal-or-intersect dtype atype
)
428 (let* ((*compiler-error-context
* use
)
429 (atype-spec (type-specifier atype
))
430 (what (when (and (combination-p dest
)
431 (eq (combination-kind dest
) :local
))
432 (let ((lambda (combination-lambda dest
))
433 (pos (position-or-lose
434 lvar
(combination-args dest
))))
435 (format nil
"~:[A possible~;The~] binding of ~S"
436 (and (lvar-has-single-use-p lvar
)
437 (eq (functional-kind lambda
) :let
))
438 (leaf-source-name (elt (lambda-vars lambda
)
440 (cond ((and (ref-p use
) (constant-p (ref-leaf use
)))
443 "~:[This~;~:*~A~] is not a ~<~%~9T~:;~S:~>~% ~S"
445 (list what atype-spec
446 (constant-value (ref-leaf use
)))))
450 "~:[Result~;~:*~A~] is a ~S, ~<~%~9T~:;not a ~S.~>"
452 (list what
(type-specifier dtype
) atype-spec
)))))))))
455 ;;; Loop over all blocks in COMPONENT that have TYPE-CHECK set,
456 ;;; looking for CASTs with TYPE-CHECK T. We do two mostly unrelated
457 ;;; things: detect compile-time type errors and determine if and how
458 ;;; to do run-time type checks.
460 ;;; If there is a compile-time type error, then we mark the CAST and
461 ;;; emit a warning if appropriate. This part loops over all the uses
462 ;;; of the continuation, since after we convert the check, the
463 ;;; :DELETED kind will inhibit warnings about the types of other uses.
465 ;;; If the cast is too complex to be checked by the back end, or is
466 ;;; better checked with explicit code, then convert to an explicit
467 ;;; test. Assertions that can checked by the back end are passed
468 ;;; through. Assertions that can't be tested are flamed about and
469 ;;; marked as not needing to be checked.
471 ;;; If we determine that a type check won't be done, then we set
472 ;;; TYPE-CHECK to :NO-CHECK. In the non-hairy cases, this is just to
473 ;;; prevent us from wasting time coming to the same conclusion again
474 ;;; on a later iteration. In the hairy case, we must indicate to LTN
475 ;;; that it must choose a safe implementation, since IR2 conversion
476 ;;; will choke on the check.
478 ;;; The generation of the type checks is delayed until all the type
479 ;;; check decisions have been made because the generation of the type
480 ;;; checks creates new nodes whose derived types aren't always updated
481 ;;; which may lead to inappropriate template choices due to the
482 ;;; modification of argument types.
483 (defun generate-type-checks (component)
485 (do-blocks (block component
)
486 (when (block-type-check block
)
487 ;; CAST-EXTERNALLY-CHECKABLE-P wants the backward pass
488 (do-nodes-backwards (node nil block
)
489 (when (and (cast-p node
)
490 (cast-type-check node
))
491 (cast-check-uses node
)
492 (cond ((cast-externally-checkable-p node
)
493 (setf (cast-%type-check node
) :external
))
495 ;; it is possible that NODE was marked :EXTERNAL by
497 (setf (cast-%type-check node
) t
)
498 (casts (cons node
(not (probable-type-check-p node
))))))))
499 (setf (block-type-check block
) nil
)))
500 (dolist (cast (casts))
501 (destructuring-bind (cast . force-hairy
) cast
502 (multiple-value-bind (check types
)
503 (cast-check-types cast force-hairy
)
507 (convert-type-check cast types
))
509 (let ((*compiler-error-context
* cast
))
510 (when (policy cast
(>= safety inhibit-warnings
))
512 "type assertion too complex to check:~% ~S."
513 (type-specifier (coerce-to-values (cast-asserted-type cast
))))))
514 (setf (cast-type-to-check cast
) *wild-type
*)
515 (setf (cast-%type-check cast
) nil
)))))))